Monte Carlo simulation of the emergency shutdown system for the high-temperature pebble-bed nuclear reactor

A theoretical model of the emergency shutdown system for the high-temperature pebble-bed nuclear reactor is presented. The stochastic trajectory of an absorbent ball has been described as a fall with ‘absorption’ along the vertical axis and with planar diffusion in the horizontal directions. Small samples of the random packing of hard spheres and the absorbent balls' trajectories in them have been simulated by the direct Monte Carlo method. The values of model parameters have been estimated from the simulated distributions of the absorbent balls' displacement vectors. The estimated values agree qualitatively with experimental data.